Tropical cyclone Nathan is moving toward the coast of Queensland and it is intensifying.  At 10:00 p.m. EDT on Wednesday the center of Tropical Cyclone Nathan was located at latitude 14.7°S and longitude 147.4°E which put it about 140 miles east of Cape Flattery, about 190 miles east-northeast of Cooktown and about 200 miles east of Cape Melville.  Nathan was moving toward the west at 7 m.p.h.  The maximum sustained wind speed was 95 m.p.h. and there were gusts to 120 m.p.h.  The minimum surface pressure was 959 mb.

Nathan intensified quickly on Wednesday and it is close to being the equivalent of a Category 2 hurricane on the Saffir-Simpson Scale.  The core of the circulation is moving over warm Sea Surface Temperatures.  The upper level winds are light and there is very little vertical wind shear.  Nathan is in a favorable environment and it has well developed upper level outflow.  It is expected to increase in intensity until it makes landfall.

A subtropical ridge building northwest of Nathan is expected to steer it west toward the cost of Queensland.  On the projected track, the center will make landfall between Cape Melville and Cooktown in 12 to 18 hours.  Nathan has the potential to bring strong winds near where the center makes landfall.  Even though the circulation is relatively small, it also has the potential to generate a significant storm surge near the location of landfall.  The strength of the circulation also will create the potential for locally heavy rainfall and flooding as the cyclone moves inland.

After making a long slow clockwise loop, Tropical Cyclone Nathan is expected to intensify and move toward Northern Queensland.  At 10:00 p.m. EDT on Tuesday the center of Tropical Cyclone Nathan was located at latitude 15.2°S and longitude 149.2°E which put it about 270 miles east of Cooktown, about 260 miles east-northeast of Cairns and about 330 miles northeast of Townsville, Australia.  Nathan was moving toward the west-southwest at 3 m.p.h.  The maximum sustained wind speed was 60 m.p.h. and there were wind gusts to 80 m.p.h.  The minimum surface pressure was 983 mb.

Wind shear had been inhibiting the re-organization of the circulation around Tropical Cyclone Nathan.  However, it has moved into a much more favorable environment and the circulation has consolidated.  Satellite imagery indicates that Nathan now looks like a classical tropical cyclone with an area of thunderstorms at its center and spiral bands rotating around the core.  Nathan is over warm Sea Surface Temperatures and in an area where the upper level winds are light.  So, further intensification is likely and rapid intensification is possible.

The steering currents around Nathan have been weak.  However, a subtropical ridge is expected to build southwest of the tropical cyclone and steer it westward toward northern Queensland.  The projected track would bring the center of Nathan to the coast near Cooktown in about 36 to 48 hours.   Nathan is expected to intensify during that time and it could be a strong tropical cyclone when it makes landfall.  It has the potential to bring strong winds and a significant storm surge when it reaches the coast.  It could also bring locally heavy rain and possibly flooding as the circulation moves inland over northeastern Queensland.

The structure of Tropical Cyclone Nathan improved on Sunday and it intensified slowly.  At 11:00 p.m. EDT on Sunday the center of Tropical Cyclone Nathan was located at latitude 13.9°N and longitude 149.8° which put it about 300 miles east-northeast of Cooktown, about 420 miles north-northeast of Townsville, Australia and about 250 miles north of Willis Island.  Nathan was moving toward the east-southeast at 3 m.p.h.  The maximum sustained wind speed was 65 m.p.h. and there were gusts to 80 m.p.h.  The minimum surface pressure was 984 mb.

Spiral bands of thunderstorms wrapped around the center of circulation and the structure of Nathan looks more well organized.  It is over warm Sea Surface Temperatures and the upper level winds are not too strong.  As a result, Nathan appears to be developing stronger upper level outflow.  The upper level outflow is pumping out mass, which is allowing the pressure to decrease and the wind speed to increase.  The environment around Nathan could support further intensification during the next 48 hours.

A ridge located northeast of Nathan is steering it slowly toward the south and that motion is likely to continue over the short term.  The winds steering the tropical cyclone could weaken in 24 to 48 hours, which could result in a period of little movement.  Later in the week a second ridge is expected to build northwest of Nathan and start to steer it westward which would move it closer to the east coast of Australia.   The projected track could bring Nathan very close to Willis Island in three or four days.

Tropical Cyclone Nathan started moving eastward away from Queensland on Saturday.  At 10:00 p.m. EDT on Saturday the center of Tropical Cyclone Nathan was located at latitude 13.4°S and longitude 148.5°E which put it about 400 miles northeast of Townsville, Australia.  Nathan was moving toward the east at 10 m.p.h.  The maximum sustained wind speed was 50 m.p.h. and there were wind gusts to 65 m.p.h.  The minimum surface pressure was 989 mb.

The circulation around Nathan showed signs of increasing organization with a long spiral band beginning to wrap around the center.  It is possible that the long period of time Nathan was stationary caused it to upwell cooler water.  As it moves eastward, the center of circulation is moving back over warmer Sea Surface Temperatures which are supplying more energy to the system.  Nathan is in an area where the upper level winds are relatively light and it has the potential to intensify during the next day or two.

A ridge located north of Nathan is steering it toward the east.  The steering currents are expected to weaken in 24 to 48 hours and Nathan could stall again.  Numerical guidance is providing conflicting indications about the longer term track.  Some guidance turns the tropical cyclone back to the southwest, while other guidance pushes the system farther to the east.

The center of Tropical Cyclone Olwyn has been moving roughly parallel to the coast of Western Australia and it is near Carnarvon.  At 11:00 p.m. EDT on Thursday the center of Tropical Cyclone Olwyn was located at latitude 24.6°S and longitude 113.4°E which put it about 20 miles northwest of Carnarvon and about 100 miles north of Denham, Australia.  Olwyn was moving toward the south-southwest at 15 m.p.h.  The maximum sustained wind speed was 100 m.p.h. and there were gusts to 120 m.p.h.  The minimum surface pressure was 959 mb.  Earlier on Thursday the airport at Learmonth measured sustained winds to 84 m.p.h. and a pressure of 970 mb when the center of Olwyn passed just to its west.

Olwyn is being steered southward by a subtropical ridge to its east.  The projected path takes the center of circulation inland and then moves it parallel to the coast.  When Olwyn moves inland it will start to weaken.  However, if there is a slight deviation of the track to the west which keeps the center of circulation over water for a longer period of time, it would keep the circulation stronger.  The latter possibility would extend the risk for wind damage farther south along the coast.  In either case, the clockwise rotation around the center and the shape of the coast could produce a significant storm surge in Shark Bay.  There is also a potential for locally heavy rainfall and flooding near the coast.

An eye appears to be forming in the center of Tropical Cyclone Olwyn and it is near hurricane intensity.  At 11:00 p.m. EDT on Wednesday the center of Tropical Cyclone Olwyn was located at latitude 18.5°S and longitude 114.8°E which put it about 210 miles northwest of Karratha and about 250 miles north-northeast of Exmouth, Australia.  Olwyn was moving toward the south-southwest at 9 m.p.h.  The maximum sustained wind speed was 70 m.p.h. and there were gusts to 90 m.p.h.  The minimum surface pressure was 978 mb.

The circulation around Olwyn became increasingly well organized on Wednesday and and eye appeared to develop.  The stronger thunderstorms are on the western side of the eye and the circulation could be pulling in a little drier air on the eastern side.  Olwyn is over warm Sea Surface Temperatures and the upper level winds are light.  So, further intensification is possible before Olwyn makes landfall.

A subtropical ridge is steering Olwyn in a generally southerly direction and that steering pattern is expected to continue.  The projected track brings the center of Olwyn near Exmouth on the coast of Western Australia in about 18 to 24 hours.  Owlyn has the potential to bring strong winds and a significant storm surge near the point of landfall.  In addition it could bring locally heavy rainfall and the potential for floods as it moves inland.

Tropical Cyclone Nathan moved slowly toward the northern coast of Queensland on Wednesday.  At 11:00 p.m. EDT on Wednesday the center of Tropical Cyclone Nathan was located at latitude 13.5°S and longitude 145.3°E which put it about 110 miles north of Cooktown, Australia and about 70 miles east of Cape Flattery.  Nathan was moving toward the west at 4 m.p.h.  The maximum sustained wind speed was 65 m.p.h. and there were gusts to 85 m.p.h.  The minimum surface pressure was 982 mb.

The eastern half of the circulation around Nathan was being affected by some of the upper level outflow from large Tropical Cyclone Pam to the east.  The outflow from Pam was creating vertical wind shear over the eastern half of Nathan and inhibiting convection on that side of the circulation.  In addition, Nathan is close enough to the coast of Queensland that interaction with land could be affecting some of the circulation on the western side of the storm.  Despite those negative influences, Nathan is over warm Sea Surface Temperatures and the wind speeds increased slightly on Wednesday.

Numerical guidance continues to suggest that a near equatorial ridge will build north of Nathan and stop its westward motion.  The ridge is projected to eventually push Nathan back toward the east later this week.  The center of Nathan is within 70 miles of the coast of Queensland, and even if it turns back toward the east it could bring high winds and a storm surge to a portion of the coast near Cape Flattery.

A low level circulation is organizing quickly in an area of thunderstorms northwest of Western Australia and the system has been classified as Tropical Cyclone Olwyn.  At 8:00 a.m. EDT on Wednesday the center of Olwyn was located at latitude16.6°S and longitude 116.1°E which put it about 280 miles north of Karratha and about 390 miles north-northeast of Exmouth, Australia.  The maximum sustained wind speed was 45 m.p.h. and there were gusts to 60 m.p.h.  The minimum surface pressure was 996 mb.

Olwyn is over warm Sea Surface Temperatures and it is in an area where the upper level winds are very weak.  The favorable environment has allowed thunderstorms to grow rapidly and the circulation has developed upper level outflow which is pumping out mass and allowing the pressure to decrease.  Owlyn is expected to remain in a favorable environment until it makes landfall in Western Australia.  It should continue to intensify and a period of rapid intensification is possible.

Olwyn is moving around the western end of a subtropical ridge which is steering it toward the south.  That general steering pattern is expected to continue for the next several days.  On its projected track, Olwyn could approach the coast of Western Australia between Onslow and Exmouth in a about 36 hours.

Olwyn has the potential to cause significant wind damage and generate a storm surge near where the center makes landfall.  In addition, it could produce locally heavy rainfall and the potential for floods as it moves inland.